The aging process modifies body composition and the inertial properties of body limbs might change accordingly. Pendular energy exchange, mechanical work and locomotion efficiency should be affected by these changes. To check this hypothesis, seven elderly subjects were asked to walk on a treadmill at five speeds ranging from 0.55 to 1.66 m s-1. The internal work is indeed reduced when calculated by using specific anthropometric tables for the elderly. The pendular recovery and external work are not affected by the anthropometric profile. Our results suggest that the mass-specific mechanical work based on anthropometric tables consistently decreases with age and consequently the greater metabolic cost is counterbalanced, in part, by decreased mechanical work, resulting in a similar locomotion efficiency.